The present invention relates to a method and a coil apparatus for inductive power transmission. The invention also relates to a vehicle comprising a coil apparatus of this type.
Although applicable to any coil apparatuses for inductive power transmission, the present invention will be presented, without loss of generality, on the basis of the example of coil apparatuses for contactless, inductive charging of batteries of electrically operated vehicles.
Electric vehicles, which nowadays are tested as prototypes or in test fleets, are equipped with coil apparatuses of this type, which comprise one or more electromagnetic coils installed in an insulating plastics housing and which are usually mounted on the vehicle underbody or are embedded therein, such that they constitute the lowest parts on the vehicle underbody. This makes it possible to start the charging process comfortably without delay as soon as the vehicle is stopped at a charging point equipped with a corresponding further coil apparatus arranged on the ground.
When traveling over curbs or poor-quality stretches of road, however, it is routinely expected in the case of road vehicles of conventional design that the underbody will contact or scrape along the curb/road surface. Such contact leads to damage at the lowest parts of the vehicle underbody. In the event of mechanical damage with damage to the insulation of the coil apparatus, an electric shock caused by insufficiently insulated voltage is to be anticipated in the event of contact. The same is true for coil apparatuses arranged on the ground, which apparatuses for example lie on the floor of a garage or on the ground at a parking space or are embedded therein and may be damaged when driven over or when scraped over. It is thus desirable to avoid the risk of electrical accidents with electric shock when using coil apparatuses for inductive power transmission.